Development of procedures for identifying pesticide toxicity in ambient waters: Carbofuran, diazinon, chlorpyrifos

Abstract

The responses of carbofuran, diazinon, and chlorpyrifos to standard acute toxicity identification evaluation (TIE) procedures were characterized. The test species was Ceriodaphnia dubia. The TIE procedures included solid‐phase extraction, recovery in methanol eluates, hydrolysis under acid and base conditions, and retention in specific methanol/water fractions. In addition, the effect of the metabolic inhibitor, piperonyl butoxide, on the toxicity of each of the pesticides was determined. Diazinon degraded quickly under acid conditions, whereas carbofuran degraded under base conditions. In both cases, concentrations were reduced to nontoxic levels within 6 h. Conversely, acidic or basic conditions were not effective in reducing the concentration of chlorpyrifos over the same time period. Solid‐phase extraction removed at least 95% of diazinon and carbofuran from solution, but was less effective with chlorpyrifos. All three pesticides eluted separately in characteristic methanol/water fractions. Piperonyl butoxide ameliorated the toxicity of diazinon and chlorpyrifos, but not carbofuran. Up to 1.5% methanol did not interfere with the protective action of piperonyl butoxide. Case studies in which these techniques were applied to ambient water samples are also described.

Application of whole effluent toxicity test procedures to ambient water quality assessment

“…The TIEs then became a routine follow-up to the detection of toxicity. The U.S. EPA protocols were modified to specifically address pesticide toxicity [12,13], metal toxicity [14], algal toxicity [15], and the toxicity associated with urban storm runoff [13].…”

Dietary transfer of fluoranthene from an estuarine oligochaete (Monopylephorus rubroniveus) to grass shrimp (Palaemonetes pugio): Influence of piperonyl butoxide

“…Previous studies involving invertebrates have demonstrated that PBO is highly toxic, with reported LC 50 values for water fleas (Ceriodaphnia dubia) and amphipods (Hyalella azteca) of 330 lg/L and 530 lg/L, respectively (Ankley and Collyard, 1995;Baily et al, 1996). By comparison, studies involving fish have demonstrated that PBO is only moderately toxic to this taxon, with reported LC 50 values ranging from 3940 lg/L in sheepshead minnow (Cyprinodon variegatus) to 11,200 lg/L in rainbow trout (Salmo gairdneri) (Erickson et al, 1988).…”

Diazinon and chlorpyrifos in urban waterways in Northern California, USA

“…Piperonyl butoxide either completely eliminated or significantly reduced toxicity in 12 of the 14 samples. In all cases, sufficient diazinon was present to account for the acute toxicity; the fact that PBO did not eliminate toxicity in all cases suggests that other toxicants were present, because 200 ppb PBO should eliminate acute toxicity at diazinon concentrations of at least 1,500 ng/L [19]. Note that these studies were carried out only on the full-strength sample, so it is not possible to determine the exact contribution of metabolically activated organophosphorus pesticides to toxicity in cases where the toxicity was not completely eliminated.…”

“…Chem. 19,2000 H.C. Bailey et al averaged at least twice as high as those in the industrial catchment (sump 111).…”

“…A subset of samples were treated with selected toxicity identification evaluation procedures to characterize the nature of toxicity. The treatments included filtration with 0.45-m filters to remove particulates [18], solid-phase extraction with C 8 solid-phase extraction columns [19], and treatment with the biochemical reagent piperonyl butoxide (PBO) [19,20], which inhibits the oxidation of phosphorothioate pesticides to the more toxic phosphate form [21]. Thus, reduction of toxicity in the presence of PBO suggests that toxicity was due to one or more metabolically activated organophosphorous pesticides.…”